I’ve always been a bit confused by duplicates.
It would be good to have the policy clarified.
I usually comment, but if I do mark them in some way then I do so with DQA (but not captive/cultivated option I think).
I prefer DQA as I think treating flags as a waste bin is more problematic than adding to casual obs.
Also it seems less aggressive for new users.
Ideally though, duplicates need a dedicated solution.